For a natural number \(m\in \mathbb {N}\) , we define the sets \(I_m:=\lbrace 0,\ldots ,m\rbrace \) ,
\(\partial I_m:=\lbrace 0,m\rbrace \) , and
\(I_m^0:=I_m\setminus \partial I_m\) . Let \(p\in \mathbb {N}\)  be the polynomial degree. We are going to
consider the Gauss–Lobatto rule with \((p+2)\)  points
(see, for example, [1]}), which is exact for polynomials
of degree at most \((2p+1)\) . The weights are denoted \(\lbrace \varpi _j\rbrace _{j\in I_{p+1}}\) 
and the nodes in \([-1,1]\)  are denoted \(\lbrace \xi _j\rbrace _{j\in I_{p+1}}\) . Recall that
\( \varpi _0 = \varpi _{p+1}= \frac{2}{(p+1) (p+2)}, \qquad \varpi _j = \frac{2}{(p+1) (p+2) (L_{p+1}(\xi _j))^2}, \quad \forall j \in I_{p+1}^0,\) 
